U.S. patent number 4,713,127 [Application Number 06/907,037] was granted by the patent office on 1987-12-15 for triplebasic propellant powder and process for the production thereof.
This patent grant is currently assigned to Fraunhofer-Gesellschaft zur Forderung der angewandten. Invention is credited to Jurgen Kremp, Dietmar Muller.
United States Patent |
4,713,127 |
Muller , et al. |
December 15, 1987 |
Triplebasic propellant powder and process for the production
thereof
Abstract
Triplebasic propellant powders consist of nitrocellulose,
nitroglycerin or an equivalently acting explosive oil and
crystalline nitroguanidino, which are processed by mixing with one
another and plasticizing the NC by means of a solvent, e.g.
acetone, as well as by kneading the mixture and subsequent shaping
to solid propellant powder bodies. In order to improve the thermal
stability, particularly the cold embrittlement behaviour, at least
one organic titanate from the group of monoalkoxy, chelate,
quaternary, neoalkoxy, cycloheteroatom or coordinated titanates
and/or at least one organic zirconate from the group of neoalkoxy
zirconates is added to the propellant powder in a proportion of
.ltoreq.2%, preferably .ltoreq.0.5%. This addition improves the
chemical stability of the propellant powder.
Inventors: |
Muller; Dietmar (Karlsruhe,
DE), Kremp; Jurgen (Vallendar, DE) |
Assignee: |
Fraunhofer-Gesellschaft zur
Forderung der angewandten (Munich, DE)
|
Family
ID: |
6280757 |
Appl.
No.: |
06/907,037 |
Filed: |
September 12, 1986 |
Foreign Application Priority Data
|
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|
|
|
Sep 12, 1985 [DE] |
|
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3532525 |
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Current U.S.
Class: |
149/98; 149/100;
149/108.8; 149/109.6; 149/95; 264/3.1 |
Current CPC
Class: |
C06B
23/006 (20130101); C06B 25/26 (20130101); C06B
25/18 (20130101) |
Current International
Class: |
C06B
25/00 (20060101); C06B 23/00 (20060101); C06B
25/26 (20060101); C06B 25/18 (20060101); C06B
025/26 () |
Field of
Search: |
;149/95,98,100,109.6,108.8 ;264/3.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lechert, Jr.; Stephen J.
Attorney, Agent or Firm: McCormick, Paulding & Huber
Claims
What is claimed is:
1. A process for preparing a triplebasic propellant powder, from
nitrocellulose (NC), an explosive oil (NGL) and crystalline
nitroguanidine (NIGU), comprising the following steps; mixing with
one another the NC, NGL and plasticising the NC by means of a
solvent, kneading the mixture to give solid propellant bodies
adding at least one organic titanate selected from the group of
monoalkoxy, chelate, quaternary, neoalkoxy, cycloheteroatom or
coordinated titanates and/or at least one organic zirconate from
the group of neoalkoxy zirconates to provide a proportion of
.ltoreq.2% by weight of such organic titanate and/or zirconate.
2. A propellant powder according to claim 1, wherein the organic
titanate and/or organic ziroonate proportion is 0.2 to 1.0 and
preferably 0.2 to 0.5% by weight.
3. A process for the preparation of a triplebasic propellant powder
according to claims 1 or 2, in which alcohol-moist NC, sensitized
NGL or the equivalently acting explosive oil, crystalline NIGU and
a solvent, e.g. acetone are fed into a discontinuously operating
kneader and homogenized, the plasticized material is intermediately
stored and then shaped to a propellant body, wherein the organic
titanate and/or zirconate is added to the kneading formulation
either directly or mixed with the solvent.
4. A process for preparing a triplebasic propellant powder
according to claims 1 or 2, in which alcohol-moist NC, sensitized
explosive oil, crystalline NIGU and a solvent, are supplied to an
extruder and continuously shaped to a propellant strand, and
wherein the organic titanate and/or zirconate is supplied to the
extruder directly, or mixed with the solvent, or mixed with the
latter and the explosive oil.
5. The propellant prepared by the process of claim 1.
6. The propellant prepared by the process of claim 4.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a triplebasic propellant powder
comprising nitrocellulose (NC), nitroglycerin (NGL) or an
equivalent explosive oil and crystalline nitroguanidine (NIGU),
which can be processed to solid propellant bodies by mixing with
one another, plastioizing the NC by means of a solvent, e.g.
acetone, as well as kneading the mixture.
Compared with singlebasic and doublebasic prepellant powders,
triplebasic propellant powders have the advantage of high power but
limited barrel erosion, these characteristics mainly being due to
the nitroguanidine content. This can range from 5% to over 50% by
weight, reference being made e.g. to types M30, M31, NQ and MNF for
the range between 45 and 53% by weight. These propellant powders
are either processed discontinuously in kneaders or continuously in
oxtrudoro to shaped bodies and in the latter case to propellant
strands, which can then be cut to give bodies from which the
propellant charges are prepared. Plasticizing and therefore
shapability are mainly determined by the nitrocellulose content
which, as a result of the solvent, e.g. acetone acquires a gel
structure and binds in the other components.
The mechanical strength and in particular the brittleness behaviour
is decisively influenced by the nitroguanidine mixed in in
crystalline form. Particularly at low temperatures, it has an
increased cold embrittlement tendency, even at conventional
temperatures of use down to -40.degree. C. When firing such
propellant powders, particularly those with a high NIGU proportion,
the cold embrittlement leads to very unfavourable interior
ballistics, which can even make the powder unusable.
SUMMARY OF THE INVENTION
The problem of the invention is to improve the embrittlement
behaviour of triplebasic propellant powders and in particular to
reduce or prevent cold embrittlement.
This problem is solved in the case of a triplebasic propellant
powder of the aforementioned structure by the addition or at least
one organic titanate from the group of monoalkoxy, chelate,
quaternary, neoalkoxy, cycloheteroatom or coordinated titanates
and/or at least one organic zirconate from the group of neoalkoxy
zirconates with a proportion of .ltoreq.2% by weight.
Practical tests on triplebasic propellant powders of the
aforementioned structure have revealed that it is possible to
completely prevent cold embrittlement at temperatures down to
-40.degree. C. and it is in particular possible to obtain better
characteristics than can e.g. be obtained by optimizing the crystal
shape and size of the nitroguanidine or e.g. by partially
dissolving the NIGU crystals Parallel tests on propellant powders,
whose cold embrittlement it was attempted to improve by adding
polymers, led to the same results as regards cold embrittlement
only being achieved when the polymer was added in a proportion of
approximately 5% by weight. However, even when the polymer was
added in a proportion of more than 2% by weight there were negative
changes in the burning behaviour, which in the case of an
equivalent in the cold embrittlement of 5% by weight even led to
such polymer-bound, triplebasic propellant powders becoming
unusable. However, as a result of the inventive addition of organic
titanates or zirconates, the burning behaviour is not impaired and
the power is retained compared with "pure" triplebasic propellant
powders. The chemical stability of the propellant powder is also in
no way impaired. A positive sideeffect was also discovered, in that
the erosion action on the weapon is reduced, which can be
attributed to titanium oxide deposits on burning. The cold
embrittlement improvement is due to the fact that the titanates and
zirconates are responsible for a better adhesion between the
plasticized fractions and the NIGU crystals and consequently the
structure and optionally also the adhesion between the crystals
becomes more stable.
A significant and usually adequate improvement to the cold
embrittlement has been obtained, on the basis of practical tests,
with an organic titanate and/or organic zirconate proportion of 0.2
to 1%, preferably 0.2 to 0.5% by weight.
It is surprising that with such a small addition there is a
significant improvement to the cold embrittlement. However, it is
obvious that such a small amount does not have any influence on the
burning behaviour and the power of the propellant powder.
As has already been indicated, triplebasic propellant powders are
essentially prepared according to two methods. In the first method
alcohol-moist NC, desensitized NGL or the equivalent explosive oil,
crystalline NIGU and a solvent, e.g. acetone are fed into a
discontinuously operating kneader, homogenized and plasticized and
optionally the plasticized material is intermediately stored. This
material is then shaped into propellant strands and then cut to
bodies or granulated. According to the invention this process is
modified in that the organic titanate and/or zirconate is added to
the kneading formulation either directly or mixed with the solvent.
As the organic titanates and zirconates are liquids, they can be
homogeneously mixed without difficulty with the remaining
components or can be added in a premix with the solvent.
In the second, continuous method, the aforementioned components are
applied to an extruder and continuously shaped to propellant powder
strands. This method also permits the production of the propellant
powder according to the invention in that the organic titanate
and/or zirconate is supplied to the extruder either directly, or
mixed with the solvent, or mixed with the latter and the NGL or the
equivalently acting explosive oil.
The improvement in the cold embrittlement of the inventively
composed and prepared propellant powders was established by loading
cylindrical test bodies axially and at right angles thereto by
means of a clearly defined falling weight with clearly defined
impact velocity, similar to the drop hammer test for measuring the
mechanical ignition behaviour. The propellant bodies were loaded at
+21.degree. C. and -40.degree. C. with a falling weight of 1 kg
from a height of fall of 0.2 to 0.5 m. Propellant powder bodies
with a seven-hole geometry were investigated (body diameter 8.6 mm
and length 19.8 mm or diameter 8.0 mm and length 19.0 mm,
individual body weight 1.30 to 1.45 g). Conclusions with regards to
the cold embrittlement behaviour can be drawn from the fragments
obtained on reaching the limit load. Triplebasic propellant powders
of a conventional structure, including those with an optimized NIGU
crystal shape and size and original comparison powders give
fragments of different size and geometry on reaching the limit load
and they have in particular a high proportion of fines and
thin-walled webs, whereas propellant powders with the composition
according to the invention and at the same limit load do not break
and do not even suffer from cracking. Tests in the ballistic bomb
with special fittings were used for further evaluation
purposes.
Apart from the improvement to the cold embrittlement behaviour,
storage tests at 90.degree. C. revealed that the weight loss, which
is a measure of the chemical stability of the propellant powder,
was very low. In the case of all the investigated tests pieces with
an addition of between 0.2 and 0.5% titanate by weight, the weight
loss was roughly within equal limits and was surprisingly lower
than in the "pure" propellant powder, from which it can be
concluded that the addition or organic titanates or zirconates
leads to a certain improvement in the chemical stability, whereas
the addition of up to 2% by weight polymers leads to a
significantly higher weight loss.
TABLE 1
__________________________________________________________________________
FORMULATION OF TRIBASIC PROPELLANTS WITH MONOALKOXY
TITANATE-ADDITIVE Nitroguanidine Additive Nitrocellulose
Nitroglycerine Wt. % Centralit I Cryolite Wt. %
__________________________________________________________________________
27.1 .+-. 1 24.1 .+-. 1 47.1 .+-. 2 1.3 0.4 0.2% Isopropyl- 25 .+-.
2 20 .+-. 4 55.0 .+-. 5 " " tri(dioctylphosphate) titanate 27.1
.+-. 1 24.1 .+-. 1 47.1 .+-. 2 " " 0.5% Isopropyl- 25 .+-. 2 20
.+-. 4 55 .+-. 5 " " tri(dioctylphosphate) titanate 27.1 .+-. 1
24.1 .+-. 1 47.1 .+-. 2 " " 0.2% isopropyl- 25 .+-. 2 20 .+-. 4 55
.+-. 5 " " triisostearoyltitanate 27.1 .+-. 1 24.1 .+-. 1 47.1 .+-.
2 " " 0.5% isopropyl- 25 .+-. 2 20 .+-. 4 55 .+-. 5 " "
triisostearoyltitanate
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
FORMULATION OF TRIBASIC PROPELLANTS WITH ADDITIVES FROM THE GROUP
OF (1) CHELATE TITANATE, (2) QUAT. TITANATE, (3) COORDINATE
TITANATE, (4) NEOALKOXY TITANATE, (5) CYCLOHETEROATOM TITANATE, (6)
NEOALKOXY ZIRCONATE Nitroguanidine Nitrocellulose Nitroglycerine
Wt. % Centralit I Cryolite Additive Wt. %
__________________________________________________________________________
27.1 .+-. 1 24.1 .+-. 1 47.1 .+-. 2 1.3 0.4 0.2 Group 1, 2, 3, " "
" " " 0.5 4, 5, 6 25 .+-. 2 20 .+-. 4 55 .+-. 5 " " 0.2 Group 1, 2,
3, " " " " " 0.5 4, 5, 6
__________________________________________________________________________
Representatives of Group 1:
Titaniumdi-(cumylphenylate)-oxyacetate-Titanium-di-(dioctylpyrophosphate)
oxyacetate, Di(dioctylphosphato)-ethylene titanate. Group 2:
Titaniumdi-(cumylphenylate)-oxacetate +
2dimethyl-aminomethylpropanol. Group 3:
Tetraisopropyldi-(dioctylphosphito)-titanate. Group 4: Neoalkoxy,
trineodecanoyltitanate. Group 5:
Dicyclo(dioctyl)-pyrophosphato-dioctyl-titanate. Group 6:
Neoalkoxytrisneodecanoyl-zirconate
Neoalkoxytris(dioctyl)-phosphato-zirconate
Neoalkoxytris-(m-amino)-phenyl-zirconate
* * * * *